Brush holders for electrical machinery



Aug. 14, 1962 T. GUTBERLET BRusH HoLDERs FOR BLECTRICAL MACHINERY Filed Oct. 30, 1959 R. m N W W.

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3 649,637 BRUH HLDERS Fm): ELECTRHCAL ll/IACHHIYEEE J Theodor Gutherlet, Giessen (Hessen), Germany, assignor to Schnnk 3; Ehe GmbH., Giessen (li-iessen}, Gerz many, a corporation of Germany Filed Get. fat), 195%, Ser. No. 849,79tl 1.1 Claims. (Cl. 310-246) This invention relates to brush holders for electrical machinery -and is particularly concerned with devices for applying thrust or force to a brush guided by a holder so as to continuously urge the brush against the cornmutator or slip rings, or the like, the device being particularly applicable to very long brushes and also to twin brushes.

In brush holders of the type wherein a thrust lever transmits force through an arcuate path to the brush, the difference between that arcuate path and the rectilinear path of the brush in the holder is usually compensated for by displacement of a thrust member on the top plane of the brush. in twin brushes, as herein disclosed, the thrust member rests in a recess in the top of the brush in order that the thrust may be applied to both parts of said brush. The difierence then between the arcuate path of said thrust member and the rectilinear path followed by the brush is usually compensated for by resiliently mounting a thrust finger in a thrust lever, but even if resilient or rubber damping members are used, as is usually the case, the said thrust finger is subjected to considerable lateral forces which alter the direction of thrust land the pressure of application, all to the end that the brushes do not wear uniformly. As a result, a holder of this type has the disadvantage that it must be provided with brushes of a relatively reduced length. Furthermore, the resilient and therefore unstable mounting of the thrust finger is not altogether satisfactory under Operating conditions.

mprovements are obtained, even with medium length brushes, for example, 65 mm. in length, by use of a contact sleeve which rests loosely in a recess or a V-shaped trough in the top of a twin brush, being applied thereto through the agency of a thrust finger which can be displaced on the thrust member to compensate for the difference between the rectilnear and arcuate movements. A disadyantage of such an arrangement is that the two brush-guiding walls must be formed with a deep recess and are therefore subjected to heavy Wear, while the rubber damping element is disposed in the sleeve to rest upon the brush top and in the Zone of greatest heating. Thus, the heat reduces the life of the damping rubber considerably. Furthermore, since the contact sleeve is loose ou the thrusting 'lever and relatively displaceable, servicing of the holder in the usual narrow commutator chambers is difficult.

According to another proposal, the difference between t'he paths described by the brush `and the thrust finger respectively c'an be compensated for by providing a link between the holder casing and the thrust lever, the thrust member being guided axially of the brush by a recess as herein disclosed, in the brush top. The arcuate path described by the lever is compensated for by a corresponding displacement of the link. However, as in the previous design, the disadvantages of this design are that the thrust finger is subjected to lateral forces and that the kinetic system is unsatisfactory and leads to a considerable drop in thrust as the brush wears. Also, the levers project a considerable distance so that the brush holder requires considerable space between the comrnutator and the casing of the machine.

According to the present invention, it is an object to obviate the above mentioned disadvantages by mounting the thrust lever on a fulcrum on the link 'which link can move freely for only a part of the brush movement due to wear and which abuts a stop during the last part of 'SJI 311491537 Patented Aug. 14, 1962 the movement, so that the thrust lever continues to operate with stationary fulcrum after said link is stopped.

Another object of this invention is to provide a brush holder for electric machinery wherein a thrust lever is carried on a fulcrum by a pivoted 'link which is stopped and after which the thrust lever continues to operate and wherein the said thrust member is guided axially of the brush by engaging in a recess in the brush.

it is another object of this invention to provide a brush holder for electric machinery wherein a thrust lever is carried on a fulcrum by a pivoted link which is stopped and after which the thrust lever continues to operate and wherein a recess is formed in twin brushes for engagement by said thrust member to guide it axially of the holder.

lt is still another object of this invention to provide a brush holder for electrical machinery wherein a thrust lever is carried on a fulcrum by a pivoted link and wherein the thrust lever is biased so that pressure is produced to counteract, during initial wear of the brush, lateral forces ordinarily applied to the brush because of the arcuate movement of said thrust lever.

Further, it is an object of this invention to provide a brush holder for electrical machinery wherein a thrust lever is carried on a fulcrum by a pivotal link and wherein a thrust member extends from said thrust lever through a resilient and vibraton damping member of insulating material.

The various objects and features of this invention will be fully understood from the following detailed descrip tion of the preferred form and application thereof throughout which description reference is made to the accompanying `drawings, in which:

HG. 1 is a side elevation of the brush holder of the present invention, showing it related to the periphery of a commutator and illustrating the extended position of the device to receive a brush of full length.

FG. 2 is a view similar to FIG. 1 and illustrates the position of the device wherein the mechanism engages a stop to thereby limit -movement of a part thereof, as later described.

FG. 3 is a view similar to FIGS. 1 and 2 and illustrates further movement of the device which takes place after the said part thereof is stopped as shown in FIG. 2.

PIG. 4 is a sectional view of the brush of the present invention and taken as indicated by line 4-4 on FIG. 1.

The brush holder of the present invention is adapted for use, generally, in dynamo-electric machines, such `as, for example, electric motors and/or generators, and in any like situation where commutation of electrical current is required. That is, the brush holder is adapted to be used in connection with commutators and slip-rings to apply pressure to a brush along its longitudinal axis, and in any other' like situations. As shown in the drawings, the invention involves, `generally, a brush holder 1 that slidably carries a brush 2, to guide it into engagement with a commutator w, a thrust lever 4, a thrust finger 5 with a thrust member 6 engageable with the brush 2, a vibration damping means 9 supporting the thrust member on the thrust lever 4, a link 8 pivoted relative to the holder i and pivotally carrying the .thrust lever 4, bias means 3 to urge the thrust lever and member into pressured engagement with the brush 2, and a stop 11 to limit movement of the link 8.

The brush holder 1 is a guide part adapted to direct the brush 2 into engagement with the periphery of the commutator w and is of the usual construction and formed of electrical insulating material or alternatively mounted on insulators (not shown). The periphery of the commutator lt? is arcuate with the holder guiding the brush 2 so that it projects radially of the commutator, the holder l and brush Z being of substantial length in order to allow for long wear of said brush. In accordance with the invention, one side of the holder is open or slotted at (see PIG. 4) in order to permit depressing of the brush 2 by the thrust finger 5, as shown in FIGS. 2 and 3, and there is a bracket 21 that projects laterally from the slotted side of the holder, at the lower end thereof, at and near the commutator, to cooperatively carry and relate the link 3, stop '11 and bias means 3.

The brush 2, as shown throughout the drawings, is a twin brush of carbon, or the like, in that it involves a pair of like brush sections 22 and 23. The cross section of the twin brush 2 is shown in FIG. 4 of the drawings, indicating the separate independent Sections 22 and `22v, as they are guided by the holder 1 and accessible through the slotted opening at 2.0. In accordance with the invention, the sections 22 and 23 are arranged face to face in lateral engagemcnt and there is a notch 22' and 23' at the upper end of each section, respectively, said notches being arcuate and cooperatively forming a semi-circular seat or recess 7. Thus, the recess 7 is at the upper end of the brush 2 and adapted to receive the thrust member 6.

The link 8 is pivotally carried by the holder 1, being pivotally connected to the bracket 21 by a pin ZS to project laterally and to swing upwardly and downwardly. The pivotal axis of the link 8 is at the lower end of the holder 1 and is disposed parallel with the commutator aXis and parallel with the adjacent side of the brush 2.

The thrust lever 4 is pivotally carried by the link 8 being pivotally connected to the outer swinging end portion of the link 8 by a pin 2d to project and swing upwardly and inwardly toward the brush 2. The pivotal supporting axis of the lever 4 is parallel with the above described pivotal axis of the link 8.

The thrust finger 5 is a continuation of and eXtends inwardly from the outer swinging end portion of the thrust lever 4 and is resiliently coupled thereto by the vibration damping means 9. In the particular case illustrated, the lever 4 and thrust finger 5 are normally related at right angles to each other, the damping means 9 comprising a body of rubber, or the like, that electrically isolates and resiliently mounts the finger 5 on the outer end portion of the lever 4. More particularly, the thrust finger 5 comprises a substantially flexible part that projects inwardly and downwardly and carries the thrust member 6 to engage the top end of the brush 2. In accordance with the invention, the thrust member 6 is carried at the terminal end of the finger 5 and is a cylindrica'lly-shaped part with its lower periphery engaged in and seated in the recess 7, the member 6 and cess 7 being formed on a common axis parallel with e axes of the above mentioned pins and 26. The bias means 3 is preferably a spring bias means and involves a simple tension spring extending between the outer end of the thrust lever 4 a'nd an anchor 32 at the bracket 21. There is a pin securing the spring 30 to the lever 4, and the anchor 32 is also a pin, or the like, located at or near the pin 25 that carries the link 4. In practice, the anchor 32 is positioned just above the pin 25 and slightly outward thereof in a lateral direction away from the bnlsh holder 1.

In accordance with the invention, the stop 11 is provided and which limits downward swinging movement of the link 8. As shown, the stop 1l1 involves a pin 35 positioned on the bracket 21 laterally outward of the pin 25 in a direction away from `the brush holder 1 and so a's to stop the link 8 in a position slightly above horizontal (normal to the longitudinal aXis of the brush 2). Thus, the link 8 reaches a stopped position after which the thrust lever 4 and finger 5 continue to move during further movement and wear of the brush 2.

The parts and elements, as above described, are related to each other and operate as follows: The twin brush 2 guided in the brush holder 1 is pressed against the commutator lt) by the tension spring 3d? acting by way of the 'lever 4, thrust finger 5 and thrust member 6 which re th engages in the recess 7 in the brush top. The difference between the areuate path described by the thrust member 6 and the rectilinear path described by the brush 2 is cornpensated for between positions shown in FIGS. 1 and 2 by the link 8 disposed between the lever 4 and the holder 1. Once position of FIG. 2 has been reached, the link 8 abuts the stop 11 and does not move while the brush is being worn between positions shown in Fl GS. 2 and 3. The dierence between the arcuate and rectilinear parts is then only a few tenths of a millimetre and is compensated for by the resilient vibration damping means 'between the lever 4 and the thrust finger 5.

From the foregoing it will be apparent that the thrust lever is spring loaded by a spring connected between said lever and the brush housing, the spring being connected to the holder in a position such that a pressure is produceo' by it which counteracts the lateral thrust on the brush caused by the arcnate movement of the thrust member. However, such pressure is insufficient to provide complete compensation for the lateral forces which are produced over the entire range of brush wear and which become substantial toward the end of brush wear. This di'liculty is overcome in the holder according to the invention by the provision of the stop which causes the thrust lever to operate with a stationary fulcrum during the final part of the brush wear, the thrust finger describing an arcuate path which is, however, of such a reduced dimension as to substantially coincide with the rectilinear brush axis. Any slight compensation which may still be needed is then provided by the damping member between the thrust finger and the thrust lever so that the brush is substantially free from lateral forces throughout the length of wear.

Having described only the typical preferred form and application of my invention, l do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear .to those skilled in the art and fall within the scope of the following claims.

Having described my invention, I claim:

1. A brush holder adapted to urge a brush into engagement with a commutator and the like, and including, a holder to shiftably carry and to guide the brush, a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting on the brush, bias means acting on the thrust lever to move the brush as it wears, and a stop engageable with the link to limit movement thereof whereby the thrust lever and thrust member turn about a stationary fulcrum during the remaining part of the brush movement.

2. A brush holder adapted to urge a brush into engagement With a commntator and the like, and including, a holder' to shiftably carry and to guide the brush, a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting in a recess in the brush, bias means acting on the thrust lever to move the brush as it wears, and a stop engageable with the link to limit movement thereof whereby the thrust lever and thrust member turn about a stationary fulcrum during the rern-aining part of the brush movement.

3. In combination, a brush holder and a twin brush adapted to be urged into engagement with a commutator and the like, said brush comprising elongate juxtapositioned Sections, and said holder comprising a pivotal link freely movable during the ini-tial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting on the Sections of the brush, 'bias means acting on the thrust lever to move the brush as it wears, and a stop engageable with the link to limit movement thereof whereby the thrust lever and thrust member turn about a stationary fulcrum during the remaining part of the brush movement.

4. In combination, a brush holder and a twin brush adapted to be urged into engagement With a commutator and the like, said brush comprising elongate juxtapositioned Sections with cooperatively related notches form- 'inlg -a recess, and said holder comprising a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link, and supporting a thrust member acting in the said recess in the Sections of the brush Sections, bias means acting on the thrust lever to move the brush as it wears, and a stop engageable with the link to limit movement thereof Whereby the thrust lever and thrust member turn about a stationary fulcrum during the remaining part of the brush movement.

5. A brush holder adapted to urge a brush into engagernent with a commutator and the like, and including, a holder to Shiftably carry and to guide the brush, a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting on the brush, and a tension member acting on the thrust lever to move the brush as it wears and anchored at the pivotal point of the link Whereby lateral pressure on the brush as caused by arcuate movement of the thrust lever is counteracted, and a stop engageable with the link to limit movement thereof Whereby the thrust lever and thrust member turn about a Stationary fulcrum during the remaining part of the brush movement.

6. A brush holder adapted to urge a lbrush into engagement With a commutator and the like, and including, a holder to Shiftably carry `and to guide the brush, a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting in a recess in the brush, and a tension member acting on the thrust lever to move the brush as it wears and anchored at the pivotal point of the link Whereby lateral pressure on the brush as caused by arcuate movement of the thrust lever is counteracted, `and a stop engageable With the link to limit movement thereof Whereby the thrust lever and thrust member turn about a Stationary fulcrum during the remaining part of the brush movement.

7. In combination, a brush holder and a twin brush adapted to be urged into engagement With a commutator and the like, said brush comprising elongate juxtapositioned Sections, and said holder comprising a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting on the Sections of the brush, and a tension member acting on the thrust lever to move the brush as it wears and anchored at the pivotal point of the link Whereby lateral pressure on the brush as caused by arcuate movement of the thrust lever is counteracted, and a stop engageable with the link to limit movement thereof whereby the thrust lever and thrust member turn about a stationary fulcrum during the remaining part of the brush movement.

8. In combination, :a brush holder and a twin brush adapted to be urged into engagement With a commutator and the like, said brush comprising elongate juxtapositioned Sections with cooperatively related notches forming a recess, and said holder comprising a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link and supporting a thrust member acting in the Said recess in the Sections of the brush Sections, and a tension member acting on the thrust lever to move the brush as it wears and anchored at the pivotal point of the link Whereby lateral pressure on the brush as caused by arcuate movement of the thrust lever is counteracted, and a stop engageable With the link to limit movement thereof whereby the thrust 'lever and thrust member turn about a stationary fulcrum during the remaining part of the brush movement.

9. A brush holder adapted to urge a brush into engagement with a commutator and the like, and including, a holder to shiftably carry and to guide the brush, a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link, a thrust finger resiliently mounted on the lever and supporting a thrust member acting on the brush, bias means acting on the thrust lever to move the brush as it wears, and a stop engageable with the link to limit movement thereof Whereby the thrust lever and thrust member turn about a stationary fulcrum during the remaining part of the brush movement.

10. A brush holder adapted to urge a brush into engagement with a commutator and the like, and including, a holder to shiftably carry and to guide the brush, a pivotal link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link, a thrust finger mounted on the lever through a vibration damping member and Supporting a thrust member acting on the brush, bias means acting on the thrust lever to move the brush as it wears, and a stop engageable With the link to limit movement thereof whereby the thrust lever and thrust member turn about a Stationary fulcrum during the remaining part of the brush movement.

11. A brush holder adapted to urge a brush into engagement with a commutator and the like, and including, a holder to Shiftably carry and to guide the brush, a pivotal 'link freely movable during the initial part of the brush movement, a thrust lever pivotally carried on the link, a thrust finger mounted on the lever through an electrical insulating and vibration damping member and supporting a thrust member acting on the brush, bias means acting on the thrust lever to move the brush as it wears, and |a Stop engageable with the link to limit movement thereof whereby the thrust lever and thrust member turn about a Stationary fulcrum during the remaining part of the brush movement.

References Cited in the file of this patent UNITED STATES PATENTS 1,l0i2,ll9 Aichele June 30, 1914 FOREIGN PATENTS 15,471 Great Britain of 1912 

